Method and apparatus for replacing insulators on energized power lines

ABSTRACT

Apparatus for replacing a suspension insulator on a tower having a davit arm supporting an attached insulator and a conductor shoe attaching an energized conductor to the insulator lower end including a non-conductive board longer than and mounted to the tower below the davit arm, struts extending between the board and the tower, and a movable slider mounted on the board, the slider supporting a jack and a conductor lifting bar attached to the jack. Without contacting any energized components, a lineman moves the slider and operates the jack to lift and support the energized components, detaches the shoe from the insulator, moves the energized components to a remote position on the board, detaches and replaces the insulator while it is supported by a helicopter, moves the slider and operates the jack to lift the shoe into alignment with the insulator and attaches the shoe to the insulator.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for replacinginsulators on energized power lines supported by a tower and, moreparticularly, to a method and apparatus which is particularly suitablefor use on a tower having insulator and conductor supporting davit armswhich are narrow and lightweight and, therefore, unsuitable forsupporting a lineman or heavy equipment.

BACKGROUND OF THE INVENTION

High voltage power transmission lines carrying voltages in the hundredsof kilowatt range have been constructed to extend from spaced towers,poles or other vertical supports (hereinafter collectively referred toas “towers”) in terrain which is often practically inaccessible to landvehicles. In recent years, a number of methods and devices have beendeveloped to facilitate the repair and maintenance of high voltage powertransmission lines which are accessed by helicopter.

Towers having davit arms are frequently employed for supporting multiplehigh voltage electrical conductors. The conductors are typicallysupported under the arms of such towers using a suspension insulator foreach conductor. Periodically, it is necessary to replace the insulatorsbecause they are visibly damaged, as part of a general maintenance planor for some other reason. Typically, an insulator is attached via a pinto each davit arm and via a pin to a shoe which supports the conductor.These pins, typically, must be manually removed by linemen placed on thetower via helicopter in order to replace the insulators. Pin removaltypically requires either bare-handed contact with energized componentsor shut down of electrical flow in the conductor. Damaged or worninsulators are typically removed from the tower via helicopter andreplacement insulators are delivered to the tower via helicopter.However, when the davit arms are narrow and lightweight, they cannotsafely support a lineman and the equipment necessary for removing andreplacing insulators. Therefore, the conventional manner of removing andreplacing insulators, where the lineman and his equipment are supportedon and work from the tower arm, cannot be used. This presents aparticular problem for safely accessing and replacing the insulators oneach davit arm.

Accordingly, there exists a need for a method and apparatus for safelyaccessing the insulator, energized conductor and their hardware,disconnecting the energized conductor from the insulator, disconnectingthe insulator to be replaced from the davit arm and obtaining andconnecting a replacement insulator, all without utilizing the davit armto support the lineman and without exposing the lineman to the risk ofcontacting the grounded tower while handling the energized conductor.

SUMMARY OF THE INVENTION

It is, therefore, a primary object of the present invention to providenovel and improved lineman support apparatus and energized conductorhandling apparatus which is deployed and removed from the tower byhelicopter and which can be used on a tower having insulator andconductor-supporting davit arms which cannot safely support a linemanand the equipment necessary for removing and replacing energizedconductor-supporting suspension insulators.

It is also an object of the present invention to provide a novel andimproved method for replacing insulators on energized power lines whichis particularly suitable for use on a tower having insulator andconductor supporting davit arms which are narrow and lightweight and,therefore, unsuitable for supporting a lineman or heavy equipment.

It is another object of the present invention to provide a novel andimproved method for replacing insulators on energized power linesaccording to which a lineman can replace a suspension insulator withoutmaking bare-handed contact with any energized components and withoutneed for shutting down electrical flow through the conductors.

It is yet another object of the present invention to provide a novel andimproved lineman support apparatus and energized conductor handlingapparatus which will allow a lineman to replace a suspension insulatorwithout making bare-handed contact with any energized components andwithout need for shutting down electrical flow through the conductors.

It is still another object of the present invention to provide a noveland improved method for replacing insulators, insulator support hardwareand conductor shoes on energized power lines which is particularlysuitable for use on a tower having insulator and conductor supportingdavit arms which are narrow and lightweight and, therefore, unsuitablefor supporting a lineman or heavy equipment.

The foregoing and other objects are achieved in accordance with thepresent invention in a method for replacing an electrical suspensioninsulator on a tower having insulator-supporting, and high voltageenergized electrical conductor-supporting, davit arms using a helicopterand at least one lineman, said insulators being supported by insulatorsupport plates attached to said davit arms and said conductors beingsupported in conductor shoes attached to the lower ends of saidsuspension insulators, comprising the steps of:

-   -   mounting an elongate, non-conductive board having inner and        outer ends to said tower with said inner end adjacent said        tower, said board being mounted sufficiently below the davit arm        supporting the insulator to be replaced to allow a lineman        standing on said board to reach said davit arm, said board        including upstanding elongate side panels for defining        therebetween and with the upper surface of said board a        generally U-shaped track, said board having a length at least        one foot longer than said davit arm;    -   mounting elongate, non-conductive, length-adjustable strut means        having inner and outer ends to said tower with said inner ends        of said strut means adjacent said tower and the outer ends of        said strut means attached near the outer end of said board, said        strut means being mounted sufficiently below the board for        providing diagonal bracing support therefor;    -   operating said length-adjustable strut means for positioning        said board horizontally and for maintaining said board        horizontally positioned on said tower;    -   supporting an elongate, non-conductive slider in said track for        movement between inner and outer ends of said board, said slider        including a planar surface parallel to said upper surface of        said board and slider or roller means for facilitating movement        of said slider along said track, the upper side of said planar        surface including jack means rigidly mounted thereon, said jack        means including a piston means vertically reciprocally movable        therewithin, and conductor lifting means rigidly connected to        said piston means for engaging said conductor;    -   using a non-conductive stick,        -   pushing said slider along said board until said jack means            and said conductor lifting means are positioned directly            underneath the conductor shoe and said conductor lifting            means is oriented to engage said conductor;        -   operating said jack means to raise said conductor lifting            means until it engages with and lifts said conductor and            said conductor shoe, whereby said conductor and conductor            shoe is supported only by said jack means and not by said            suspension insulator;        -   detaching the suspension insulator from the conductor shoe            and operating said jack means to lower saidconductor lifting            means for separating said insulator from said conductor and            conductor shoe;        -   pushing said slider toward the outer end of the board and            away from said insulator a sufficient distance to allow a            lineman access to said suspension insulator without            contacting the energized conductor or conductor shoe;    -   attaching said suspension insulator to a hovering helicopter,        detaching the suspension insulator from said insulator support        plate and removing the suspension insulator from said tower via        helicopter;    -   delivering a replacement insulator via helicopter to said tower,        attaching said replacement insulator to said insulator support        plate and detaching said replacement insulator from said        helicopter;    -   using a non-conductive stick,        -   moving said slider along the board from the outer end of the            board until the conductor lifting means, which is supporting            the conductor and conductor shoe, is positioned directly            underneath the lower end of the replacement insulator;        -   operating said jack means to raise conductor lifting means            until the conductor shoe is aligned with the lower end of            said replacement insulator; and        -   attaching the conductor shoe to the lower end of said            replacement insulator, operating said jack means to lower            conductor lifting means for separating it from said            conductor and conductor shoe and moving said slider along            said board away from said insulator and energized conductor.

In another aspect of the present invention, the method includes thesteps of:

-   -   positioning a lineman on the outer end of said board after said        slider supporting said conductor and conductor shoe is pushed to        the outer end of said board, said lineman equalizing his        electrical potential with that of said conductor and replacing        the conductor shoe before the conductor and conductor shoe are        attached to said replacement insulator.

In still another aspect of the present invention, there is providedapparatus for replacing an electrical suspension insulator on a towerhaving insulator-supporting and high voltage energized electricalconductor-supporting davit arms wherein said suspension insulators aresupported by said davit arms and said conductors are supported inconductor shoes attached to the lower ends of said suspensioninsulators, said apparatus comprising:

-   -   an elongate, non-conductive board having a planar upper surface        and inner and outer ends, said inner end including means for        mounting said board to said tower, said board including elongate        side panels projecting above said planar surface for defining        between said side panels said upper surface of said board a        generally U-shaped track, said board having a length at least        one foot longer than the davit arm supporting the insulator to        be replaced;    -   elongate, non-conductive, length-adjustable strut means having        inner and outer ends, said inner end including means for        mounting said strut means to said tower with said outer ends of        said strut means attached near the outer end of said board, said        strut means adapted to be mounted to said tower below said board        for providing diagonal bracing support therefor; and    -   an elongate, non-conductive slider mounted in said track for        movement between inner and outer ends of said board, said slider        including a planar surface parallel to said upper surface of        said board and slider or roller means between said board upper        surface and said slider planar surface for facilitating movement        of said slider along said track, the upper side of said planar        surface including jack means rigidly mounted thereon, said jack        means including a piston means vertically reciprocally movable        therewithin, and conductor lifting means rigidly connected to        said piston means for engaging said conductor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a typical tower having narrow andlightweight davit arms for supporting high voltage power transmissionlines via suspension insulators.

FIG. 2 is a perspective view of the lineman supporting and energizedconductor handling apparatus of the present invention.

FIG. 3 is a partial top plan view of the lineman supporting andenergized conductor handling apparatus of the present invention.

FIG. 4 is a sectional view taken along line A-A of FIG. 3.

FIG. 5 is a bottom perspective view of an energized conductor sliderforming a part of the lineman supporting and energized conductorhandling apparatus of FIG. 2.

FIG. 6 is a perspective view of a conductor lifting and supportingassembly forming a part of the lineman supporting and energizedconductor handling apparatus of FIG. 2.

FIG. 7 is a perspective view of the inboard end of board support strutsshowing the manner in which they are pivotally mounted to a tower.

FIG. 8 is a perspective view of the pivotal connection between theoutboard end of the support struts and the lineman support board.

FIG. 9 is a perspective view of the inboard end of a lineman supportboard showing the manner in which it is pivotally mounted to a tower.

FIG. 10 is a perspective view of an illustrative davit arm supportingtower bracket including a mounting tray for receiving the inboard end ofeither the lineman support board or the support struts.

FIG. 11 is a perspective view of the lineman supporting and energizedconductor handling apparatus of FIG. 2 mounted to a tower before workhas begun to replace the insulator or hardware.

FIG. 12 is a perspective view of the apparatus of FIG. 2 mounted to atower showing a lineman removing the conductor shoe pins which attachthe conductor and conductor shoe to the suspension insulator.

FIG. 13 is a perspective view of the apparatus of FIG. 2 mounted to atower showing the energized conductor and conductor shoe detached fromthe insulator and supported by the conductor handling apparatus, whichhas been positioned near the outboard end of the lineman support boardand spaced from the lineman by a safety arc shield.

FIG. 14 is a perspective view as in FIG. 13 after the insulator has beenremoved and replaced and a lineman transported to and emplaced on theoutboard end of the lineman support board prior to replacing theinsulator shoe.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 there is shown a more or less typical steel latticetower 10 for supporting multiple high voltage conductors. The latticetower 10 includes several (three are shown in FIG. 1) vertically spacedapart conductor-supporting davit arms 12 extending from at least oneside (FIG. 1 shows davit arms extending from two sides) of tower 10.Frequently, the davit arms are narrow and lightweight and have upperdiagonal supports 13 between the end of the arms 12 and the tower 10.Sometimes tower 10 is supported by guide wires or cables (not shown)attached to the ground. Each conductor 14 is supported by a suspensioninsulator 16 depending from each of the davit arms 12. Typically, aninsulator support plate 18 attached to the davit arms 12 supports theinsulators 16 and the insulators are connected via pins to the insulatorsupport plate 18. Likewise, a conductor shoe 20 supports the conductor14 and the bottom of each suspension insulator 16 is connected via pinsto the conductor shoe 20. It will be appreciated that conductor 14 isrelatively heavy and its weight places the suspension insulator 16 intension, making it very difficult to pull the conductor shoe pins andthe insulator support plate pins in order to remove and replace theinsulator. Generally, when replacing a suspension insulator 16, theconductor 14 to which it is attached must be supported in some mannerother than by the suspension insulator 16 in order to create slack insuspension insulator 16 to allow unpinning of the conductor shoe 20 fromsuspension insulator 16 and unpinning and removal of suspensioninsulator 16 from insulator support plate 18 of davit arm 12.

It will be appreciated that due to their structure, the davit arms areneither strong nor sturdy. Accordingly, it is not practical to placeeither a lineman or equipment on the davit arms 12 in an effort to usethe arms as a base of operations to remove and replace the insulatorsuspended therefrom. Moreover, inasmuch as the conductor is energizedduring insulator removal and replacement and since the tower 10 isgrounded, a lineman on the tower 10 must take care to avoid simultaneouscontact with the tower 10 and any energized element, such as theconductor, conductor shoe, conductor shoe pins, and the like.

Accordingly, referring to FIGS. 2-6, the present invention provides aboard 22, which is an elongate, lightweight, non-conductive fiberglassboard, desirably having a downwardly opening, channel-likecross-section, comprising a pair of elongate flanges 24 depending fromopposite longitudinal sides of the board web 25 for defining a generallyinverted U-shaped cross-section. Board 22 is cantilevered from the tower10 with its flat web 25 facing upwardly and its flanges 24 pointingtoward the ground. Desirably, the upper surface of web 25 includes anon-slip surface. Erection of board 22 to tower 10 can be accomplishedby mounting board 22 to tower 10 in any conventional manner using abracket means 26 (see FIGS. 9 and 10) which is rigidly mounted to tower10, e.g., using J-clamps 26, chain tighteners, nylon straps or othermeans. Usefully, board 22 is mounted at a point about 6′ below the davitarm 12 supporting the insulator 16 to be removed and replaced. A pair ofadjustable length support struts 28 are diagonally positioned betweenboard 22 and tower 10 with one end 28 a of the struts 28 mounted to thetower 10 at least 4 feet below the board 22 and the other end 28 bpivotally mounted near the outboard end (as used herein the term“outboard” or “outer” end refers to the end remote from tower 10 and theterm “inboard” or “inner” end refers to the end most closely adjacenttower 10) of the board 22 to provide diagonal bracing support for theboard 22. Struts 28 can be mounted to tower 10 in any conventionalmanner using a bracket means 26′ (see FIGS. 7 and 10) which is rigidlymounted to tower 10, e.g., using J-clamps, chain tighteners, nylonstraps or other means. Typically, board 22 has a length from at leastone foot (1′) longer up to about eight feet (8′) longer than the davitarm 12 from which the insulator 16 to be replaced is suspended. Thelength of board 22 depends in part upon the maintenance operations to beperformed and, in part, upon the voltage in the energized conductor. Forexample, if the conductor shoe 20 will not be replaced, then a shorterboard, as little as 1′-4′ longer than davit arm 12 will suffice, as willbe more fully discussed hereinafter. On the other hand, if the conductorshoe 20 is to be replaced, then a longer board is required, e.g., 6′-8′longer than the davit arm, as will be discussed more fully hereinafter.Board 22 desirably has a non-slip upper surface and has a minimum widthof about 12″.

To increase the strength of board 22 a pair of longitudinally extendingelongate stiffener panels 27 are attached to opposite elongate flanges24 from the outboard end 22 b of board 22 and extending along the lengthof board 22. In addition, a transversely extending elongate stiffenerpanel 27 a is attached to the ends of elongate flanges 24 at outboardend 22 b and extends between the outboard ends of longitudinallyextending stiffener panels 27. Stiffener panels 27 and 27 a projectabove web 25 of board 22 at least a sufficient distance to definebetween them a track in which a slider 30 can slide along web 25.Although stiffener panels 27 and 27 a may be attached in anyconventional manner, desirably they are adhesively secured to flanges24. A second pair of elongate stiffener panels 29 extend longitudinallyalong and are attached to stiffener panels 27 from a location near theoutboard end 22 b of board 22, e.g., about 2-3 feet from its outboardend 22 b, and extend about 2-3 feet toward the inboard or mounting end22 b of board 22. Stiffener panels 29 project below stiffener panels 27and include a series of longitudinally spaced apart apertures 29 a towhich one end 28 b of struts 28 can be pivotally mounted, ashereinbefore discussed. Like stiffener panels 27 and 27 a, stiffenerpanels 29 may be attached in any conventional manner although,desirably, they are adhesively secured to stiffener panels 27.

An elongate slider 30, desirably having an upwardly opening,channel-like cross-section, comprises a pair of upstanding flanges 31along opposite longitudinal sides of slider web 33 for defining agenerally U-shaped cross-section. Slider 30 is dimensioned to rest uponand slide on web 25 of board 22 between longitudinally extendingstiffener panels 27. Slider 30, desirably, has a length of 1-2 feet, isformed of non-conductive materials and includes slider panels 32positioned on the underside of slider web 33 between the web 25 of theboard 22 and the web 33 of slider 30 such that slider 30 is freelyslidable along the length of board 22. It will be appreciated that whileslider panels 32 may be formed of nylon, felt, teflon or other lowfriction materials, other forms of sliding or roller means can beutilized to allow slider 30 to easily move along the upper web surface25 of board 22. For example, for use with very heavy conductors, smallwheels (not shown) may be substituted for slider panels 32 to facilitatethe sliding of the underside of web 33 along the upper surface of web25. Stop means 34 are provided at the free end of the board 22 toprevent slider 30 from sliding off board 22. In the preferred form ofthe invention, as hereinabove described, the function of stop means 34is performed by transverse stiffener 27 a. However, any suitable stopmeans capable of preventing slider 30 from sliding off board 22 at freeend 22 b can be used. In addition, slider 30 is prevented from rising upoff of web surface 25 by transversely extending flanges 27 b projectinginwardly from stiffener panels 27. Desirably, slider 30 includes atransverse upstanding flange 35 extending between slider flanges 31 atthe inboard end of slider 30 for mounting a lifting ring 37 thereon.

A hydraulic jack 36 is rigidly mounted, as by bolts, upon web 33 ofslider 30 and a conductor lifting bar 38 is desirably welded to theupper end of piston 36 a of jack 36. Preferably, conductor lifting bar38 comprises an elongate bar 38 a having at each end a pair of opposedupwardly extending fingers 38 b, the fingers of each pair being spacedapart in a direction perpendicular to the longitudinal extent of bar 38a, and the upper ends of each of the fingers 38 b being flared outwardlyaway from the other finger 38 b of the pair. In this manner the flaredupper ends of fingers 38 b can receive and support conductor 14 withconductor shoe 20 positioned between the two pairs of fingers 38 b andspaced above elongate bar 38 a. As will become apparent from thediscussion which follows, the slider 30 can be slid along board 22 toposition jack 36 directly underneath conductor shoe 20 and conductorlifting bar 38 can be rotated (together with piston 36 a) to align thetwo pairs of fingers 38 a with conductor 14. Hydraulic jack 36 can thenbe operated to lift conductor lifting bar 38 until fingers 38 b engageconductor 14 and the weight of conductor 14 and conductor shoe 20 issupported by jack 36, and not by suspension insulator 16.

Referring to FIGS. 7 and 8, support struts 28 comprise elongate tubularsupport members 40, desirably of rectangular cross-section and formed ofnon-conductive materials, such as fiberglass, and length-adjustablestrut extenders 41 for lengthening or shortening struts 28. The outboardend 40 b of each support member 40 is pivotally attached, e.g., via abolt, to one of the apertures 29 a in stiffener 29 on each side of board22. The inboard end 40 a of each support member 40 engages adjustablestrut extenders 41. In a preferred form of the invention, adjustablestrut extenders 41 comprise a piston 42 reciprocally operable within ahydraulic cylinder 44, which form the outboard end portion 46 b ofelongate rams 46 which mount struts 28 to bracket means 26′ rigidlyaffixed on tower 10. Desirably, solid metal bar inserts 48 having amatching cross-section to the cross-section of tubular support members40 project into, and extend outwardly from, the hollow ends 40 a,b ofeach tubular support member 40 and are attached to tubular supportmembers 40 to provide strong and durable end attachments therefor. Theportion of each insert 48 within the hollow end of each tubular supportmember 40 is preferably bolted to the support member 40 to maintain itrigidly in place, although other forms of attachment are also suitable.Desirably, the end of insert 48 projecting from inboard end 40 a ofsupport member 40 includes an adapter 56 attached thereto, preferably bywelding, to facilitate its engagement with piston 42. A hydraulic pump50 is connected to each hydraulic cylinder 44 via discharge and supplyhoses for supplying non-conductive hydraulic fluid to each hydrauliccylinder 44 for lengthening or shortening each support strut 28 and, inturn, for raising, lowering and/or leveling board 22. Hydraulic pump 50is desirably mounted on tubular support members 40 within reach of alineman on tower 10 or on a ladder supported by tower 10 to facilitateits use during installation, removal and adjustment of board 22.

In a preferred embodiment of the invention, the inboard end portion 46 aof each ram 46 terminates in a transversely extending cylindricaltubular segment 52 such that the tubular segments 52 at the inboard endsof rams 46 are transversely spaced apart. Tubular segments 52 and theends of rams 46 are received within the open top 54 a of an elongatemounting tray 54, which is mounted on strut bracket means 26′. Tray 54is desirably rectangular in cross-section and enclosed on its other fivesurfaces, except that each end surface 54 b includes an aperture 54 ctherein. A retaining rod 62 extends through the apertures 54 c inmounting tray 54 and through tubular segments 52 to pivotally mount ends28 a of struts 28 to mounting tray 54 and, therefore, to board bracketmeans 26′ in order to retain struts 28 pivotally affixed to tower 10. Inthe absence of rod 62, tubular segments 52 are forced against the lower,innermost corner 54 d of tray 54 by the weight of board 22.

Referring to FIG. 9, board 22 is desirably pivotally mounted to tower 10by a pair of transversely spaced apart elongate legs 58 extending towardtower 10 from inboard end 22 a of board 22, the legs 58 terminating in atransversely extending tubular element, such as cylindrical tube 60.Legs 58 desirably extend from board mounting end 22 b toward tower 10outwardly and downwardly in a gentle arcuate curve. Tube 60 and the endsof legs 58 are received within the open top 55 a of a second elongatemounting tray 55, which is mounted on board bracket means 26. Secondtray 55 is desirably rectangular in cross-section and enclosed on itsother five surfaces, except that each end surface 55 b includes anaperture 55 c therein. A retaining rod 62 extends through the apertures55 c in mounting tray 55 and through tube 60 to pivotally mount end 22 aof the board 22 to mounting tray 55 and, therefore, to board bracketmeans 26 in order to retain board 22 pivotally affixed to tower 10.

Referring to FIG. 10, frequently the vertical support elements of tower10 comprise vertical channels supporting horizontal davit arms, thechannels opening inwardly of the tower and providing a flat web surfacefacing outwardly. Board 22 is usefully mounted to tower 10 at a locationalong tower 10 which is about six feet below the davit arm 12 supportingthe insulator 16 to be removed and replaced. Struts 28 are usefullymounted to tower 10 at a location along tower 10 which is at least fourfeet below board 22. Both board 22 and struts 28 are mounted to tower 10using bracket means 26, 26′ which are rigidly affixed to tower 10 usingany one of a number of conventional mounting means previously discussed.In a preferred embodiment of the invention, brackets 26, 26′ comprise ametal plate 64 having one face flush with the web of the tower channel,clamps 66 extending from the rear of the tower channel around its sideflanges and bolts 68 securing the metal plate 64 to the clamps 66. Metalplate 64 includes an apertures-containing flange 67 projecting from itssurface away from tower 10. The tower facing surface 54 e, 55 e ofreceiving tray 54, 55 includes an apertures-containing flange 69projecting rearwardly toward metal plate 64. Receiving tray 54, 55mounts to bracket means 26, 26′ by sliding flanges 67 and 69 along eachother until apertures 70 of flange 67 are in vertical registry withapertures 72 of flange 69 and pins 74 are inserted through the alignedapertures to mount receiving tray 54, 55 to metal plate 64. Similarlyconfigured bracket means can be used in circumstances where the verticalsupport element of the tower presents a corner instead of a flat websurface for mounting the board and struts thereto. In such a case, twoweb plates (not shown) extend rearwardly from the rear surface of metalplate 64 for defining an angle therebetween corresponding to the angledefined by the tower corner and metal plate 64 is mounted to thevertical tower element with the web plates adjacent each side of thetower element defining the corner. Clamps 66 engage the rear corners ofthe tower structure and bolts 68 secure the metal plate 64 to the clamps66.

Referring to FIG. 11, to remove and replace a suspension insulator 16when the conductor 14 is energized, initially, linemen, ladders andtools are flown to tower 10 via helicopter. Thereafter, bracket means26, 26′ and chain hoists 76 are flown out to tower 10. The first step isto rigidly affix bracket means 26, 26′ such as are described herein, toa vertical support of tower 10. A first bracket means 26 is positionedabout six feet below the davit arm 12, which supports the insulator 16to be removed and replaced, for mounting board 22 to tower 10. A secondbracket means 26′ is positioned at least four feet below the firstbracket means 26 for mounting the inboard ends 28 a of the diagonalsupport struts 28. For safety purposes, it is desirable to attach afirst ratchet chain hoist 76 to the davit arm 12 which is supporting theinsulator 16 to be removed and replaced with the first chain hoist 76supporting upper bracket means 26 and to attach a second ratchet chainhoist 76′ to the next lower davit arm 12 (which is typically above thelower bracket means 26′) or to tower 10 above the lower bracket means26′ with the second chain hoist 76′ supporting lower bracket means 26′.Next, the board 22, with support struts 28 on opposite longitudinalsides of board 22 pivotally mounted near one end 28 b to one ofapertures 29 a in stiffener panels 29 and with hydraulic pumps 50attached to struts 28, is lifted by a helicopter to be mounted on thepair of vertically spaced apart bracket means 26, 26′ which are alreadyin place on tower 10.

At least when there is a davit arm 12 immediately below the davit armsupporting the insulator 16 to be replaced, the free end of one ofstruts 28 is initially tied to board 22 to keep it out of the way as thehelicopter positions board 22 for mounting within mounting tray 55 onbracket means 26. This is important since board 22 is to be mountedunder davit arm 12 with support struts 28 extending diagonallydownwardly towards tower 10 on opposite sides of the next lower davitarm 12. Thus, if the board 22 were to be lifted and emplaced by ahelicopter with struts 28 extending on opposite sides of davit arm 12,the next lower davit arm 12 would interfere with at least one of thestruts 28 as the board 22 approaches tower 10. With one strut 28 tied upto the board 22, the helicopter can approach the tower 10 and davit arm12 from the side of the depending strut 28 without the other strut 28striking the next lower davit arm 12. The helicopter positions the board22 relative to tower 10 until elongate legs 58 with attachedtransversely extending tubular cylinder 60 projects into the uppermounting tray 55. At this stage, the tied-up strut 28 is untied fromboard 22 and permitted to pivot downwardly about the bolt attaching itto aperture 29 c in stiffener 29. The free end of board 22 is thenlowered until the inboard ends 28 a of both depending struts 28 andattached tubular end segments 52 are received within the lower mountingtray 54. The weight of the board forces tubular segments 52 into thelower innermost corner 54 b of lower mounting tray 54. Retaining rod 62is then inserted through the apertures 55 c in upper mounting tray 55and through cylindrical tube 60 to pivotally mount and retain inboardend 22 a of board 22 in upper mounting tray 55. The board is thenleveled side to side and outboard to inboard by a lineman on tower 10separately operating hydraulic pumps 50 on each of struts 28. Desirably,slider 30, with hydraulic jack 36 bolted to slider 30 and conductorlifting bar 38 welded to piston 36 a of jack 36, is locked onto board 22at a position near inboard end 22 a of board 22 prior to board 22 beinglifted to tower 10 by a helicopter. Board 22 has at least one aperture78 a in its inboard end portion and slider 30 includes an aperture 80 inweb 25 which can be moved into registry with inboard board aperture 78 aand a locking pin 82 inserted through apertures 78 a and 80 to lockslider 30 in position near inboard end 22 a of board 22 during movementof board 22.

Using a non-conductive shotgun stick, a lineman stands on either tower10 or board 22 near tower 10 and pushes slider 30 along board 22 untiljack 36 and conductor lifting bar 38 are positioned directly underneaththe conductor shoe 20, which is pinned to the lower end of suspensioninsulator 16, with the fingers 38 b of conductor lifting bar 38 beneathand aligned with conductor 14. Utilizing the shotgun stick, a linemanoperates hydraulic jack 36 to raise conductor lifting bar 38 untilfingers 38 b engage and lift conductor 14 and conductor shoe 20. Whenthis occurs, conductor 14 and conductor shoe 20 are supported only byhydraulic jack 36 and not by the suspension insulator 16, therebycreating slack in suspension insulator 16. Referring to FIG. 12, stillusing a non-conductive shotgun stick, a lineman removes the cotter pinand load pin attaching the suspension insulator 18 to the conductor shoe20. Hydraulic jack 36 is then reversed by a lineman with thenon-conductive shotgun stick and operated to lower conductor lifting bar38 in order to separate suspension insulator 16 from the conductor 14and conductor shoe 20, which are now supported by conductor lifting bar38. The hydraulic jack 36 is then locked.

Referring to FIG. 13, using the shotgun stick, a lineman pushes slider30, supporting the conductor 16 and conductor shoe 20, toward theoutboard end of board 22 and away from insulator string 16 to allow alineman access to the insulator string 16 without contacting orsubstantial risk of contacting the energized conductor 14 or conductorshoe 20. Board 22 has at least one aperture 78 b in its outboard endportion and slider 30 includes an aperture 80 in web 25 which moves intoregistry with outboard board aperture 78 b as the slider 30 slides alongboard 22. Using the shotgun stick a lineman inserts a locking pin 82through the slider web aperture 80 into outboard board aperture 78 b tolock slider 30 in position remote from the insulator string 16. Outboardboard aperture 78 b is sufficiently far away from the insulator 16 sothat a lineman can work on the insulator without contacting theenergized conductor 14 or conductor shoe 20. Desirably, a lineman theninstalls a safety arc shield 84, which is an insulated partition,between insulator 16 and the energized conductor 14 and conductor shoe20 and isolates these energized elements by inserting the lower marginof shield 84 into vertically oriented guides 86 extending upwardly fromstiffener panels 29. At this point a lineman walks out along board 22 tothe suspension insulator 16, attaches the insulator 16 to a line from anearby hovering helicopter and pulls the pins attaching the insulator 16to the insulator support plate 18. The helicopter flies away from tower10, removing the worn or damaged insulator 16 from tower 10. If desired,the lineman then removes the old insulator support plate 18 and installsa new one in its place. The helicopter returns with a replacementinsulator string 16, which the lineman pins to the insulator supportplate 18 and then detaches the replacement insulator 16 from thehelicopter.

Referring to FIG. 14, after the replacement insulator 16 has beeninstalled or, in some circumstances, when it is being installed by alineman, if it is desired to replace the conductor shoe 20, a lineman istransported by helicopter to a location on the outboard end 22 b ofboard 22 where the energized conductor 14 and conductor shoe 20 arepositioned such that conductor 14 and conductor shoe 20 are locatedbetween the lineman and the arc shield 84. When it is desired to replaceconductor shoe 20, board 22 must be sufficiently long to accommodate thelineman on its outboard end 22 b. In such a case, board 22 should be atleast 6′-8′ longer than davit arm 12, depending upon the voltage in theenergized conductor. It will be appreciated that, if conductor shoe 20is not to be replaced, there would be no need to position a lineman onthe outboard end 22 b of board 22, in which case board 22 need only beabout 1′-4′ longer than the davit arm, depending upon the voltage in theenergized conductor. Two linemen may safely be supported on board 22 atthe same time only when conductor 14 is small in diameter, e.g., 1″ orless, and lightweight. If conductor 14 is relatively large in diameter,e.g., more than 1″, and heavy or where tower 10 is on inclined ground,such as a steep hill, only one lineman at a time is permitted on board22. Using an insulated hot stick and a conductive clamp, the lineman onthe outboard end 22 b of board 22 equalizes the electrical potentialbetween himself and the energized conductor 14 in a well known manner,removes the old conductor shoe 20 and installs a new one in its place.Thereafter, the lineman is removed by helicopter from the outboard end22 b of board 22.

A lineman is next positioned on board 22 between the tower 10 and arcshield 84. The lineman removes safety arc shield 84 from guides 86 and,using a non-conductive shotgun stick, pulls slider 30 along board 22until jack 36 and conductor lifting bar 38, supporting conductor 14 andconductor shoe 20, are positioned directly underneath the lower end ofreplacement suspension insulator 16. Utilizing a shotgun stick, alineman operates hydraulic jack 36 to lift conductor lifting bar 38until the conductor shoe 20 is aligned with the lower end of theinsulator string 16. Still using a non-conductive shotgun stick, alineman re-inserts the load pin and cotter pin for re-attaching thesuspension insulator 16 to the conductor shoe 20. With thenon-conductive shotgun stick, hydraulic jack 36 is then reversed andoperated to lower conductor lifting bar 38 to separate fingers 38 b fromconductor 14, which is now again supported by suspension insulator 16.Using a shotgun stick, slider 30 is slid inwardly toward tower 10 untilaperture 80 in web 33 is in registry with inboard board aperture 78 a,at which time a lineman inserts a locking pin 82 through apertures 78 aand 80 to lock the slider 30 in position near inboard end 22 a of board22.

This procedure is repeated for each suspension insulator 16 by removingboard 22 and attached struts 28 from tower 10 using a helicopter andinstalling them below the next lower davit arm 12 which supports aninsulator 16 to be removed and replaced. One useful time-savingtechnique is to initially mount bracket means 26 about six feet beloweach davit arm 12, commence insulator replacement on the uppermost davitarm utilizing the uppermost bracket means 26 to mount board 22 below theuppermost davit arm 12 and utilizing the next lower bracket means 26 formounting the support struts 28 to tower 10. In this manner, when work iscompleted on the uppermost davit arm 12, the board 22 may berepositioned and mounted in the bracket means which last supported thesupport struts 28 and the next lower bracket means may be utilized formounting the support struts 28 to tower 10. When work is to commence onthe lowermost davit arm 12, the uppermost mounting bracket is removedfrom its position below the uppermost davit arm 12 and mounted on tower10 at least 4 feet below the lowermost bracket means for mounting thesupport struts 28 to tower 10.

While the present invention has been described in terms of specificembodiments thereof, it will be understood that no limitations areintended to the details of construction or design other than as definedin the appended claims.

1. A method for replacing an electrical suspension insulator on a towerhaving insulator-supporting, and high voltage energized electricalconductor-supporting, davit arms using a helicopter and at least onelineman, said insulators being supported by insulator support platesattached to said davit arms and said conductors being supported inconductor shoes attached to the lower ends of said suspensioninsulators, comprising the steps of: mounting an elongate,non-conductive board having inner and outer ends to said tower with saidinner end adjacent said tower, said board being mounted sufficientlybelow the davit arm supporting the insulator to be replaced to allow alineman standing on said board to reach said davit arm, said boardincluding upstanding elongate side panels for defining therebetween andwith the upper surface of said board a generally U-shaped track, saidboard having a length at least one foot longer than said davit arm;mounting elongate, non-conductive, length-adjustable strut means havinginner and outer ends to said tower with said inner ends of said strutmeans adjacent said tower and the outer ends of said strut meansattached near the outer end of said board, said strut means beingmounted sufficiently below the board for providing diagonal bracingsupport therefor; operating said length-adjustable strut means forpositioning said board horizontally and for maintaining said boardhorizontally positioned on said tower; supporting an elongate,non-conductive slider in said track for movement between inner and outerends of said board, said slider including a planar surface parallel tosaid upper surface of said board and slider or roller means forfacilitating movement of said slider along said track, the upper side ofsaid planar surface including jack means rigidly mounted thereon, saidjack means including a piston means vertically reciprocally movabletherewithin, and conductor lifting means rigidly connected to saidpiston means for engaging said conductor; using a non-conductive stick,pushing said slider along said board until said jack means and saidconductor lifting means are positioned directly underneath the conductorshoe and said conductor lifting means is oriented to engage saidconductor; operating said jack means to raise said conductor liftingmeans until it engages with and lifts said conductor and said conductorshoe, whereby said conductor and conductor shoe is supported only bysaid jack means and not by said suspension insulator; detaching thesuspension insulator from the conductor shoe and operating said jackmeans to lower saidconductor lifting means for separating said insulatorfrom said conductor and conductor shoe; pushing said slider toward theouter end of the board and away from said insulator a sufficientdistance to allow a lineman access to said suspension insulator withoutcontacting the energized conductor or conductor shoe; attaching saidsuspension insulator to a hovering helicopter, detaching the suspensioninsulator from said insulator support plate and removing the suspensioninsulator from said tower via helicopter; delivering a replacementinsulator via helicopter to said tower, attaching said replacementinsulator to said insulator support plate and detaching said replacementinsulator from said helicopter; using a non-conductive stick, movingsaid slider along the board from the outer end of the board until theconductor lifting means, which is supporting the conductor and conductorshoe, is positioned directly underneath the lower end of the replacementinsulator; operating said jack means to raise conductor lifting meansuntil the conductor shoe is aligned with the lower end of saidreplacement insulator; and attaching the conductor shoe to the lower endof said replacement insulator, operating said jack means to lowerconductor lifting means for separating it from said conductor andconductor shoe and moving said slider along said board away from saidinsulator and energized conductor.
 2. A method, as claimed in claim 1,including the step of replacing said insulator support plate after theinsulator to be replaced is removed and before the replacement insulatoris attached.
 3. A method, as claimed in claim 1, including the steps ofpositioning a lineman on the outer end of said board after said slidersupporting said conductor and conductor shoe is pushed to the outer endof said board, said lineman equalizing his electrical potential withthat of said conductor and replacing the conductor shoe before theconductor and conductor shoe are attached to said replacement insulator.4. A method, as claimed in claim 3, wherein said board has a length atleast one to eight feet longer than said davit arm.
 5. A method, asclaimed in claim 1, further including the step of installing a insulatedpartition between the insulator and said energized conductor andconductor shoe on the outer end of said board.
 6. A method, as claimedin claim 1, wherein mounting said board to said tower includes the stepof rigidly affixing board-supporting bracket means to a vertical supportof said tower and mounting the inner end of said board to saidboard-supporting bracket means.
 7. A method, as claimed in claim 6,wherein mounting said strut means to said tower includes the step ofrigidly affixing strut means-supporting bracket means to a verticalsupport of said tower below said board-supporting bracket means andmounting the inner ends of said strut means to said strutmeans-supporting bracket means.
 8. A method, as claimed in claim 7,wherein said board with strut means attached is lifted onto said towerby a helicopter and is supported by said helicopter while the inner endsof said board and said strut means are mounted to their respectivebracket means.
 9. A method, as claimed in claim 6, wherein saidboard-supporting bracket means includes an elongate mounting tray havingan open top, said board including elongate legs extending from its innerend toward said tower, and including the step of inserting said legsinto the open top of said mounting tray for pivotally mounting andretaining said legs within said mounting tray.
 10. A method, as claimedin claim 9, wherein said mounting tray extends transversely of saidboard and includes opposed end panels, said end panels each including anaperture therein, said legs terminating in a transversely extending,elongate tubular element and including the step of inserting a retainingrod through said apertures and said tubular element for pivotallymounting and retaining said legs within said mounting tray.
 11. Amethod, as claimed in claim 7, wherein said strut means-supportingbracket means includes an elongate mounting tray which extendstransversely of said strut means, said tray having an open top, saidstrut means comprises at least two elongate, non-conductive,length-adjustable struts having inner and outer ends, the outer ends ofthe at least two struts being pivotally mounted on opposite sides of andnear the outer end of said board, the inner end of each strutterminating in a transversely extending, elongate tubular segment, thetubular segments at the inner ends of said struts being transverselyspaced apart, and including the step of inserting said tubular segmentsinto the open top of said mounting tray.
 12. A method, as claimed inclaim 1, wherein said board is mounted to said tower at least six feetbelow said davit arm.
 13. A method, as claimed in claim 1, wherein saidstrut means are mounted to said tower at least four feet below saidboard.
 14. A method, as claimed in claim 1, wherein said slider is onsaid board when said board is mounted to said tower.
 15. A method, asclaimed in claim 14, including the step of locking said slider againstmovement on said board when said board is mounted to said tower.
 16. Amethod, as claimed in claim 15, wherein said board includes an aperturenear its inner end, said slider includes an aperture in its planarsurface and including the step of moving said slider along said boardinto registry with said inner end aperture and inserting a locking pinthrough said apertures to lock said slider against movement near theinner end of said board.
 17. A method, as claimed in claim 1, includingthe step of locking said slider against movement on said board when saidslider is supporting said conductor and said conductor shoe near theouter end of said board.
 18. A method, as claimed in claim 17, whereinsaid board includes an aperture near its outer end, said slider includesan aperture in its planar surface and including the step of moving saidslider along said board into registry with said outer end aperture whensaid slider is pushed toward the outer end of said board and away fromsaid insulator and inserting a locking pin through said apertures tolock said slider against movement near the outer end of said board. 19.A method, as claimed in claim 10, including the step of tying one ofsaid struts to said board prior to mounting said board to said tower,lifting said board onto said tower by a helicopter and supporting saidboard by said helicopter while the inner end thereof is mounted to saidboard-supporting bracket means, untying the tied-up strut and mountingthe inner ends of said struts to said strut mounting tray.
 20. Apparatusfor replacing an electrical suspension insulator on a tower havinginsulator-supporting and high voltage energized electricalconductor-supporting davit arms wherein said suspension insulators aresupported by said davit arms and said conductors are supported inconductor shoes attached to the lower ends of said suspensioninsulators, said apparatus comprising: an elongate, non-conductive boardhaving a planar upper surface and inner and outer ends, said inner endincluding means for mounting said board to said tower, said boardincluding elongate side panels projecting above said planar surface fordefining between said side panels said upper surface of said board agenerally U-shaped track, said board having a length at least one footlonger than the davit arm supporting the insulator to be replaced;elongate, non-conductive, length-adjustable strut means having inner andouter ends, said inner end including means for mounting said strut meansto said tower with said outer ends of said strut means attached near theouter end of said board, said strut means adapted to be mounted to saidtower below said board for providing diagonal bracing support therefor;and an elongate, non-conductive slider mounted in said track formovement between inner and outer ends of said board, said sliderincluding a planar surface parallel to said upper surface of said boardand slider or roller means between said board upper surface and saidslider planar surface for facilitating movement of said slider alongsaid track, the upper side of said planar surface including jack meansrigidly mounted thereon, said jack means including a piston meansvertically reciprocally movable therewithin, and conductor lifting meansrigidly connected to said piston means for engaging said conductor. 21.Apparatus, as claimed in claim 20, wherein said elongate side panelsinclude a portion near the outer end of said board which projects belowsaid board, said portion including a series of longitudinally spacedapart apertures for pivotally attaching the outer ends of said strutmeans to said board.
 22. Apparatus, as claimed in claim 20 wherein saidelongate side panels comprise first elongate stiffener panels attachedto the sides of said board and extending between its inner and outerends.
 23. Apparatus, as claimed in claim 22, wherein said side panelsfurther include second elongate stiffener panels extendinglongitudinally along, attached to and projecting below said firststiffener panels, said second stiffener panels including a series oflongitudinally spaced apart apertures near the outer end of said boardfor pivotally attaching the outer ends of said strut means to saidboard.
 24. Apparatus, as claimed in claim 22, wherein said boardcomprises a pair of elongate flanges depending from oppositelongitudinal sides of said board for defining a generally invertedU-shaped board cross-section, said first elongate stiffener panels beingattached to said flanges.
 25. Apparatus, as claimed in claim 22, whereinsaid first stiffener panels include transversely extending flangesprojecting inwardly therefrom above said slider when said slider ismounted on said board for preventing said slider means from rising upoff of said planar upper surface of said board.
 26. Apparatus, asclaimed in claim 20, wherein said outer end of said board includes stopmeans for preventing said slider from sliding off the outer end of saidboard.
 27. Apparatus, as claimed in claim 26, wherein said stop meanscomprises a transversely extending elongate panel projecting above saidplanar surface of said board and attached to said board at its outerend.
 28. Apparatus, as claimed in claim 20, wherein said board has alength between one and eight feet longer than the davit arm supportingthe insulator to be replaced.
 29. Apparatus, as claimed in claim 20,wherein said board includes elongate legs extending from its inner endtoward said tower, said legs terminating in a transversely extending,elongate tubular element.
 30. Apparatus, as claimed in claim 29, furtherincluding board-supporting bracket means for rigid mounting to avertical support of said tower, said board-supporting bracket meansincluding an elongate board mounting tray extending transversely of saidboard for receiving and retaining said tubular element therewithin. 31.Apparatus, as claimed in claim 30, wherein said elongate board mountingtray includes opposed end panels, said end panels each including anaperture therein, and a retaining rod extending through said aperturesand said tubular element for pivotally mounting and retaining said legswithin said mounting tray.
 32. Apparatus, as claimed in claim 30,further including means for mounting said board mounting tray to saidbracket means.
 33. Apparatus, as claimed in claim 20, wherein said strutmeans comprises at least two elongate, non-conductive, length-adjustablestruts having inner and outer ends, the outer ends of the at least twostruts being pivotally mounted on opposite sides of and near the outerend of said board, the inner end of each strut terminating in atransversely extending, elongate tubular segment, the tubular segmentsat the inner ends of said struts being transversely spaced apart. 34.Apparatus, as claimed in claim 33, further including strut-supportingbracket means for rigid mounting to a vertical support of said tower,said strut-supporting bracket means including an elongate strut mountingtray extending transversely of said struts for receiving said tubularsegments therewithin.
 35. Apparatus, as claimed in claim 34, whereinsaid elongate strut mounting tray includes opposed end panels, said endpanels each including an aperture therein, and a retaining rod extendingthrough said apertures and said tubular segments for pivotally mountingand retaining said struts within said mounting tray.
 36. Apparatus, asclaimed in claim 34, further including means for mounting said strutmounting tray to said bracket means.
 37. Apparatus, as claimed in claim20, wherein said strut means comprises at least two elongate,non-conductive, length-adjustable struts having inner and outer ends,each said strut including a piston reciprocally operable within ahydraulic cylinder intermediate its ends for increasing or decreasingthe length of said strut.
 38. Apparatus, as claimed in claim 37, furtherincluding a hydraulic pump connected to each hydraulic cylinder viadischarge and supply lines, each said hydraulic pump being mounted tosaid strut near said tower.
 39. Apparatus, as claimed in claim 20,wherein said slider comprises a pair of elongate flanges upstanding fromopposite longitudinal sides of said planar surface for defining agenerally U-shaped slider cross-section.
 40. Apparatus, as claimed inclaim 39, wherein said slider flanges are longitudinally adjacent saidelongate side panels when said slider is mounted in said track. 41.Apparatus, as claimed in claim 20, wherein said slider includes sliderpanels formed of low friction material attached to the underside of saidplanar surface.
 42. Apparatus, as claimed in claim 20, wherein saidconductor lifting means comprises an elongate bar having two spacedapart pairs of opposed, upwardly extending fingers for engaging saidconductor.
 43. Apparatus, as claimed in claim 42, wherein said opposedfingers of each pair are spaced apart in a direction perpendicular tothe longitudinal extent of said bar and the upper ends of each fingerare flared outwardly away from the other finger of the pair. 44.Apparatus, as claimed in claim 20, including locking means forpreventing slider movement along said board, said locking meanscomprising an aperture in the planar surface of said slider and at leastone aperture in said planar surface of said board, side slider beingmovable along said board until the aperture in said slider aligns withan aperture in the board, and a locking pin extending through saidaligned apertures to lock said slider in place on said board. 45.Apparatus for replacing an electrical suspension insulator on a towerhaving insulator-supporting and high voltage energized electricalconductor-supporting davit arms wherein said suspension insulators aresupported by said davit arms and said conductors are supported inconductor shoes attached to the lower ends of said suspensioninsulators, said apparatus comprising: an elongate, non-conductive boardhaving a planar upper surface and inner and outer ends, said inner endincluding means for mounting said board to said tower, said boardincluding elongate side panels projecting above said planar surface fordefining between said side panels and said upper surface of said board agenerally U-shaped track, said elongate side panels including a portionnear the outer end of said board which projects below said board, saidportion including a series of longitudinally spaced apart apertures,said board having a length between one foot and eight feet longer thanthe davit arm supporting the insulator to be replaced; said boardincluding elongate legs extending from its inner end toward said tower,said legs terminating in a transversely extending, elongate tubularelement, said apparatus further including board-supporting bracket meansfor rigid mounting to a vertical support of said tower, saidboard-supporting bracket means including an elongate board mounting trayextending transversely of said board for receiving and retaining saidtubular element therewithin, elongate, non-conductive, length-adjustablestrut means comprising at least two elongate, non-conductivelength-adjustable struts having inner and outer ends, said outer ends ofeach of said at least two struts being pivotally mounted on oppositesides of and near the outer end of said board to one of saidlongitudinally spaced apart apertures, the inner end of each strutterminating in a transversely extending, elongate tubular segment, thetubular segments at the inner ends of said struts being transverselyspaced apart, said strut means being mounted to said tower below saidboard for providing diagonal bracing support therefor; said apparatusfurther including strut-supporting bracket means for rigid mounting to avertical support of said tower below said board, said strut-supportingbracket means including an elongate strut mounting tray extendingtransversely of said struts for receiving said tubular segmentstherewithin; and an elongate, non-conductive slider mounted in saidtrack for movement between inner and outer ends of said board, saidboard including stop means for preventing said slider from sliding offthe outer end of said board, said slider including a planar surfaceparallel to said upper surface of said board and slider or roller meansbetween said board upper surface and said slider planar surface forfacilitating movement of said slider along said track, the upper side ofsaid planar surface including jack means rigidly mounted thereon, saidjack means including a piston means vertically reciprocally movabletherewithin, and conductor lifting means rigidly connected to saidpiston means for engaging said conductor.
 46. Apparatus, as claimed inclaim 45, wherein said conductor lifting means comprises an elongate barhaving two spaced apart pairs of opposed, upwardly extending fingers forengaging said conductor.
 47. Apparatus, as claimed in claim 46, whereinsaid opposed fingers of each pair are spaced apart in a directionperpendicular to the longitudinal extent of said bar and the upper endsof each finger are flared outwardly away from the other finger of thepair.
 48. Apparatus, as claimed in claim 45, including locking means forpreventing slider movement along said board, said locking meanscomprising an aperture in the planar surface of said slider and at leastone aperture in said planar surface of said board, side slider beingmovable along said board until the aperture in said slider aligns withan aperture in the board, and a locking pin extending through saidaligned apertures to lock said slider in place on said board.